This invention relates to a process for removing metal contaminants such as nickel and vanadium from a hydrocarbon feed stock, e.g., heavy crude, resid, and the like, thereby upgrading the feedstock for a variety of further refinery operations such as fluidized catalytic cracking, hydrodesulfurization, etc.
It is well known that heavy crude oils, as well as products from extraction and/or liquefaction of coal and lignite, products from tar sands, products from shale oil and similar products may contain metals such as vanadium and nickel. The presence of the metals make further processing of heavier fractions difficult since the metals generally act as poisons for catalysts employed in processes such as catalytic cracking, hydrogenation or hydrodesulfurization. Consequently, a number of strategies have been developed to deal with the problem posed by the presence of metal contaminants in hydrocarbon oil feed stocks.
One approach calls for passivating the catalyst with an additive which reduces the tendency of the deposited nickel to catalyze the formation of coke and hydrogen and, where the catalyst is of the porous aluminosilicate zeolite variety, to immobilize vanadium and prevent or inhibit it from migrating to the zeolite framework where it causes activity loss. Illustrative of this approach are the passivation procedures disclosed in U.S. Pat. Nos. 4,025,458; 4,031,002; 4,111,845; 4,141,858; 4,166,806; 4,167,471; 4,207,204; 4,208,302; 4,394,324; and 4,396,496.
Another approach to the problem of metal contamination in a heavy crude feed stock is to add a substance to the feed stock which will form an oil insoluble precipitate with the metal contaminants. In many processes of this type, the metal-containing oil remains in the heavy crude feed stock even while the latter is undergoing further processing, e.g., catalytic cracking. Examples of such a procedure are described in U.S. Pat. Nos. 4,036,740; 4,148,717; 4,192,736; 4,321,128; 4,399,024; 4,419,225; 4,421,638; 4,432,890; 4,446,006; 4,454,025; 4,464,251; 4,465,589; 4,518,484; 4,522,702; and 4,529,503.
Heretofore, it has not been known to contact a metal-containing liquid hydrocarbon feed stock with a water-soluble phosphorous-containing compound dissolved in a substantial amount of water relative to the amount of oil to be treated and in this way, to remove contaminating metal(s) from the oil by their reaction or formation of a complex with the phosphorous-containing compound. Although it is known from U.S. Pat. No. 4,522,702 to contact a 40-80 weight percent aqueous solution of phosphorous acid demetalating agent with heavy crude oil, the amount of water employed is negligible compared to the amount of oil being treated.